TRVs for an awkward old house

[SDMCF]

The heating system in our large old house is a ground source heat pump feeding a mixture of old cast iron and slightly more modern (but still old) pressed steel radiators. The pipework is iron. There is no zoning, and I am not even sure if this is a single or twin pipe system. All the pipe runs are hidden in the flooring, with pipes just coming up out of the floor by the rads. There is one rad with no valves at all and the remainder have manual valves. I am considering fitting TRVs, preferably a programmable type, to reduce heating costs. I realise that these won't fit in style-wise very well, but I am not particularly bothered by that.
I have gathered a fair amount of information from old threads about TRVs but I still have, as you guessed, a few questions:

1. Are TRVs available for three-quarter and half-inch inch iron pipe? Where would I get these from?

2. What should I look for in a TRV? How do I distinguish between a good valve and a bad one? What make(s) are good, and what should I avoid?

3. Do I need to fit TRVs on all rads? We have over 20 rads downstairs (3/4 inch pipework) and the same upstairs (half-inch pipework) so this isn't going to be a cheap project. Where should I buy these from - is this a large enough quantity to go to a trade supplier or the manufacturer?

4. Are TRVs a straight replacement for the existing manual valves? Iron pipe is a bit more difficult for me to work with than copper and I want to minimise the pipework changes. Ideally I want to avoid cutting new threads on existing pipes as it may be tricky to turn my dies close to a wall.

5. What exactly do I need to buy to have programmable TRVs? It looks like I have to buy a manual TRV plus a seperate programmable head for it. Is that right?

6. Is it worth doing more than just the valves? Would I gain anything by changing some or all of the radiators at the same time? If a modern radiator of the same size puts out more heat than my old rads I assume the circulating water can be cooler, which might suit the heat pump better.

7. Can anyone comment on this kit? I like the idea of a single thermostat controlling multiple valves, because I can see that multiple rads will need the same scheduling.

8. Does this project make sense financially? Will it really reduce our heating bill? How much better is the programmable option than just fitting TRVs?

9. What else do I need to know? What else do I need to buy? What else should I consider doing as part of this project?

 

[dcawkwell]

My advice would be rip the lot out and put modern radiators
and controls in.

 

[denso13]

Where would I get these from?

In Finland? Absolutely no idea, maybe more luck at http://www.finlandforum.org/. Obviously the nearer the arctic circle you are the colder it is, ergo, the more important it is to find the right answer.

 

[SDMCF]

Where would I get these from?

In Finland?

No, or at least unlikely. I am thinking about UK suppliers.

 

[SDMCF]

My advice would be rip the lot out and put modern radiators and controls in.

Why?

 

[ALEC1]

What is the current control strategy?..

I would expect a GSHP to have compensation controls, so no TRVs would be necessary...as thes vary the radiator temperature

 

[SDMCF]

The heat pump has a system to relate the flow temperature in the CH to the outside ambient temperature. This is done by defining a so-called curve (actually 2 straight lines) like a graph. The pump runs to this 24 hours per day. I can change that curve to suit the house but really that is a commissioning exercise. The pump has a control to move the curve up or down a few degrees, as a temporary adjustment. Again that is something that is rarely changed. Then there is a single room thermostat, which is a bit of a joke really in a large house. So really there is very little control currently. There is no timer or temperature set-back facility.

 

[ALEC1]

I think you are missing the point of the weather compensation as it is called... not your fault though..

several things to consider:

1) GSHP can't produce great amounts of heat so the heating is run to two temperatures all of the time...the objective is to produce a stable and comfortable temperature and at the same time not to need to provide intense heat from an auxiliary source.

2) If you reduce the heat input into one room with a TRV then the walls of the other rooms will leach heat putting more load on to heated room radiators.

3) If your energy bills are high insulate the place and run it at a lower temperature...

what you have is the only way to run a heating system with high efficiency and stable internal temperatures, purely because it matches heat generated to heat lost to the outside..

all other systems need to over heat something to gain a reasonable room temperature

I would google weather compensation and speak to the manufacturers...

 

[SDMCF]

Thanks for your comments Alec. I may well have missed the point; perhaps that is why I am here

I do understand the need to avoid the heat pump needing to run its auxiliary heating mechanism, but I still think it should be possible to reduce heating costs. Currently the whole house is at the same temperature, and that temperature is the same all day. Having parts of the house at a lower temperature, at least some of the time, must reduce my energy usage. If/when I need to warm up those rooms it is possible to do that without having the GSHP use its secondary heating. I can turn off the secondary heating completely for example, or set it only to run under extreme conditions.

I also realise that some heat will leak from a heated room to an adjacent unheated room. Overall, though, the heating requirement will go down.

The house is as well insulated as it can reasonably be, with thick loft insulation, additional wall cladding inside and out, double exterior doors, etc etc. Insulation can always be increased of course, but my feeling is that I would get fairly low returns from additional insulation, and major changes would be needed to get any significant improvement.

Are you saying that fitting TRVs will not reduce my heating costs?

 

[ALEC1]

I doubt they will save much...and quite possibly cause problems else where with pumps and higher return temperatures. You could just turn off a couple of radiators though...Or throttle them right back with limited flow

The best way to save energy is run the system at lower temperatures, and make sure the timings reflect your lifestyle, and more money on insulation... This from a heating technician...

 

[Agile]

You seem to have some very fixed views on your system.

Clearly you already have the ability to vary house temperature but you dont bother to do that.

Could I ask you how many people live there? Do you really need to heat all the rooms ALL the time? Is it a mental institution where everyone is there all the time?

A very obvious solution is to lower the temperature overnight. You can, but you dont do that! Why not?

Tony

 

[SDMCF]

You seem to have some very fixed views on your system.

Clearly you already have the ability to vary house temperature but you dont bother to do that.

Fixed views? Well yes, in so far as I know the system, and what I can change.
Why would I want to vary the whole house temperature? I want the rooms that are in use to be at the temperature we find comfortable. I only want to drop the temperature in unoccupied rooms.

Could I ask you how many people live there? Do you really need to heat all the rooms ALL the time? Is it a mental institution where everyone is there all the time?

3 of us live here.
No, I don't need to heat all the rooms all the time. That is why I am looking at programmable TRVs, as a way to lower the temperature of some of the rooms, some of the time. (In rooms that are rarely used the rads are turned down manually most of the time).
This isn't a mental institution (not sure why that is relevant but perhaps you know more abut such places than I do) but there is someone here almost all the time. I work at home as does my wife 50% of the time.

A very obvious solution is to lower the temperature overnight. You can, but you dont do that! Why not?

Two reasons. One is that I have no automatic way of doing it. I would have to change the setting manually every night. The other is that I have no way of getting the temperature back up ready for when we get up in the morning. The heating won't start to bring the house back up to temperature until I manually reset it after getting up.

 

[SDMCF]

You could just turn off a couple of radiators though...Or throttle them right back with limited flow

Yes, I can do that. Indeed I do do that in rooms that are rarely used. With the best will in the world though, that isn't a solution for rooms that are in regular use; adjusting dozens of rads every day is not something that gets done.

The best way to save energy is run the system at lower temperatures, and make sure the timings reflect your lifestyle, and more money on insulation... This from a heating technician...

The house is at the temperature we want. Sure we could save money by being cold, but that isn't what I am trying to do.
I can't make sure the timings reflect our lifestyle because there is no timer in the system. That is why I am looking at programmable TRVs. I don't see any other practical way of putting in any sort of time-based control.
Adding more insulation is an ongoing process, but we have reached the stage where significant insulation improvements are not possible without major changes to the house. Any further insulation changes are likely to be minor.

 

[Agile]

95% of people in the UK turn off their heating overnight!

All that needs is a £30 timeclock.

That will save about 25% of your heating bill.

Your fixed views include not doing what everyone else does to keep their heating bills within their budget.

Your savings will come from not heating at certain times.

You already can tamper with valves to lower heat output. TRVs will not do anything new in spite of their high cost to install.

Tony

 

[dcawkwell]

My advice would be rip the lot out and put modern radiators and controls in.

Why?

Not worth messing about with old c**p. Get the system upgraded
it will simply work much better.